His post, to Russian-language social network VKontakte, warns that those running the stalls can't protect themselves with ownership papers that he claims are fake.

"The demolition of illegal structures in Moscow is a good example of the fact that truth, legacy, and the history of our country is not sold in Russia," Sobyanin, a member of the ruling United Russia party, says in the post. "You can't hide behind property papers you clearly acquired fraudulently. Let's return Moscow to Muscovites. Its parks, squares, streets. Open, beautiful, loved."

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But Artur Aipetov, a member of the Moscow Chamber of Advocates, is disputing Sobyanin's claim. In an earlier interview with the Kommersant daily, he claimed that the demolished stalls had all the necessary documents and thus should have been protected from demolition under the Russian Constitution unless a court ruled otherwise.

"Mr. Sobyanin lost every court case on demolition of real estate in 2015," Aipetov added.

In December, authorities changed the Civil Code, which now states that the city government may demolish any structure if it deems it to be "samostroi," or "self-built." However, Aipetov said that only courts can make such decisions, and so far they have not done so.

While some have defended Sobyanin's move as appropriate, others have expressed anger at the mayor's line of defense.

On February 10, two men protested in front of the mayor's office in an action they called "You can't hide behind papers."

On Twitter, a local opposition deputy suggested that Sobyanin's statement raised the specter of conversations like the following:

"You are arrested, immediately found guilty, and now we will execute you."

"But according to the Constitution, the court…"

"You can't hide behind papers!"

Another Twitter user argued that Russian authorities use Sobyanin's principle in the area of foreign policy, too.

"I'm taking away Crimea. And don't hide behind the paper of the Budapest memorandum," the tweet reads, a reference to the document in which post-Soviet Russia promised "to respect the independence and sovereignty and the existing borders of Ukraine."

The Russian Anticorruption Foundation, headed by opposition leader Aleksei Navalny, tweeted copies of documents suggesting that two of Sobyanin's daughters own three apartments in Moscow and St. Petersburg. A 2013 investigation by the foundation claimed that one of the Moscow apartments cost $5.3 million, while the St. Petersburg property cost $3.5 million under the prevailing exchange rates.

Maksim Vorontsov, a representative of the Center for Efficient Use of State Property, told Radio Baltika that they already have around 1,500 requests to free up sites that are occupied by allegedly illegal structures.